Performing voir dire on someone you are having a discussion is odd. I don’t ask people I’m debating vegan adjacent topics with if they eat meat, that can be statistically presumed. I also don’t assume they can’t say anything true because they have an objective of wanting to continue to eat meat, and that’s often laid bare during or even at the start of discussion. Facts exist separately from the people stating them. Hypocrites can be right. People with biases can be right, and everyone has biases.
I am a vegan but I had been arguing against livestock use from an environmental perspective for many years before becoming a vegan or even a reductionist. In my mind eating animals was something like using disposable plastic. I participated in the use of animals and plastics but thought the only recourse was a legal one. Arguments of animal ethics are what ultimately brought me around to the idea that a personal boycott was ethically obligatory, because the harm to individuals from individuals was easier to see. Though after learning some ideas from utilitarianism related to statistics and commutative events as well as ideas from virtue ethics about modeling behavior and living heterodoxy my stance on boycotts or at least reduction in other areas has changed as well.
I’ll avoid responding to your arguments on the main subject because it would pressure you to respond when you’ve made it clear that you don’t want to continue having the discussion based on who I am. But I’m hoping I’ve answered your important question and given you something to think about on the topic of intellectual honesty.